θάλασσα, πέλαγος.θάλασσα is the more general word, indicating the sea or ocean as contrasted with the land or shore. It may be applied to small bodies of water. πέλαγος is the open sea, the uninterrupted expanse of water, in contrast with the portions broken by islands or with partly inclosed bays. The prominent thought is said by Trench to be breadth rather than depth. Noteworthy is the distinction between the two words in Mat. xviii. 6.